The statements in this section merely provide background information related to the present disclosure and can not constitute prior art.
WO 2009/103528 A2 discloses different blade geometries for axial turbomachines, including compressors of axial turbomachines. It discloses in particular a geometry in which the blade's leading edge has a sinusoidal S-shaped profile. This interpretation combines blade profiling across its overall section (or its chord) as well as perpendicular to it. In other words, this interpretation combines both so-called “sweep” and “lean” profiles respectively. The so-called “sweep” profile is along its length by a “displacement” of the section in a direction along its axial chord. The “displacement” mentioned above is essentially an offset in a given direction of the stack of blade sections along its length, the offset possibly changing direction. The so-called “lean” profile is along its length by a “displacement” of the section in a direction perpendicular to that of its axial chord. This combination of geometry has been shown as being able to reduce secondary vortices, leakage losses and shock losses. It should be noted that the shock losses cannot, in principle, affect the compressor blades of low-pressure turbomachines but only the fan and those of the transonic compressor upstream of the combustion chamber, or the turbine blades downstream of the combustion chamber. This interpretation does not suggest any exact blade profile parameters and, moreover, does not detail the precise effect of each of the profiling mechanisms disclosed.
U.S. Patent Application No. 2010/0215503 A1 discloses a “sweep” blade profile for transonic or supersonic applications. This interpretation focuses on reducing the combined shock losses to maintain the blade's integrity. It identifies that profiling towards the front of the blade (“forward sweep”) causes stress concentration at the leading edge at the blade root; this stress concentration is primarily due to the blade's center of gravity being shifted forwards. To solve this problem, this interpretation provides a “sweep” profile towards the back at the outer part of the blade to compensate for the shift in the center of gravity.
In the case of subsonic applications, such as those found in boosters, including low-pressure compressors of axial turbomachines, flow losses are virtually nonexistent. However, other types of losses are present; these include vortex losses generated by rotor blade tip leakage as well as secondary losses associated with the fluid flow along the inner and outer walls of the fluid stream.